In an article in the April 1993 issue of the New England Journal of Medicine it is estimated that 97 million Americans habitually snore. Of these, some 16 million are thought to be afflicted with sleep apnea. Sleep apnea is a condition in which there is a complete cessation of breathing during rest.
Snoring itself, absent apneic episodes, is destructive. Obvious is the effect of snoring on the spouse or mate of the snorer. Restless, intermittent sleep patterns caused by a spouse's snoring binges serve to breed resentment in relationships and produce daytime irritability and sleepiness. Marital problems may extend into the sexual arena, where this part of the relationship becomes strained after decisions are made to sleep in separate bedrooms, limit travel or family outings, and otherwise avoid partners in situations where their snoring would be troublesome or embarrassing.
Sleep-induced apnea compounds the problems associated with snoring. There are two forms of sleep apnea. In one form, breathing is halted when the respiratory muscles temporarily cease to function. But the most common form of sleep apnea, called obstructive apnea, arises from a blockage of the oropharyngeal airway. With either form, increasing levels of carbon dioxide in the blood ultimately triggers a resumption in respiration, usually accompanied by gasping, wheezing breaths. The snorer is momentarily awakened at the conclusion of the apneic episode, only to fall almost immediately back to sleep to then repeat the cycle.
Besides the effects associated with mere snoring, persons with sleep apnea are likely to suffer additional personal and economic harms. In critical cases, sleep apnea can contribute to cardiac arrhythmia and even death, and as a consequence of the numerous nightly sleep disruptions, of which the snorer may not even be consciously aware, those with sleep apnea may experience severe daytime drowsiness which may lead to accidents and injuries. This chronic sleepiness translates into economic harm through poor job performance. Persons with sleep apnea are more apt to be late to work and distracted during working hours. They take more sick leave, and usually give less attention to detail.
Obstructive sleep apnea largely afflicts overweight men, although it can effect men and women of any stature. During sleep, tissues in the mouth and throat, which may have become weakened, enlarged, or flabby, relax causing the airway to become occluded, thus inducing the apneic episode. Only when the amount of carbon dioxide in the blood rises to a level sufficient to provoke the breathing center of the brain, does normal respiration resume. As stated above, in severe cases, death may result.
Many approaches have been taken in addressing the problem of snoring and sleep apnea, ranging from simple weight loss, which has been shown to somewhat reduce snoring and apneic episodes in overweight persons, to the use of continuous positive air pressure applied through the nares, to radical surgical approaches such as tracheostomy and uvulopalatopharygoplasty. But by far the most widely used, and most extensively developed, approach includes the utilization of various oral cavity devices designed to, in differing manners, reduce or eliminate snoring and, consequently, sleep-induced apneic events.
Of the oral cavity appliances, some, such as U.S. Pat. Nos. 3,434,470 and 5,056,534 function to control the amount of air capable of being moved through the mouth, either lessening the intake volume of air to an extent wherein the person is incapable of producing a snore, or shutting off completely the passage of air through the mouth unless the jaw is opened to a degree sufficient to prohibit oropharyngeal occlusion. Other types of devices, such as U.S. Pat. Nos. 3,132,647 and 4,715,368, operate by physically depressing and constraining the tongue of the wearer to prevent occlusion of the airway. Still others, examples of which are U.S. Pat. Nos. 4,304,227 and 4,676,240, act to maintain an open airway by retaining the tongue in a position extending forward of the teeth.
The problems with these apparatuses are obvious. Any prevention or restriction of airflow through the mouth is not an option for persons with allergies or other conditions which limit the volume of air that can be breathed through the nasal passages. And, as is readily imaginable, the devices functioning to depress the tongue also function to cause gagging, and are too uncomfortable for most. Further, as most people are not accustomed to sleeping with their tongue stretched outside their mouth, the tongue retention devices are awkward and their appearance startling.
The more successful oral cavity appliances are those that serve to set the mandible in an open and forward position relative to the normal posture of the jaw during sleep. U.S. Pat. No. 4,901,737 discloses such a device. The appliance of the '737 patent comprises a rigid, acrylic V-shaped wedge molded to the entire mandibular dentition and a portion of the maxillary dentition. The mandibular incisal (cutting) edge is embedded from cuspid to cuspid, with a lip extending over the labial (toward the lip) surface of the mandibular incisors. The occlusal (contacting) surfaces and lingual (toward the tongue) cusps of all mandibular teeth are embedded, with the appliance extending over the lingual surfaces and extending downwardly into the lingual vestibule. Crosswise palatal stiffening is provided by heavy dental wire, and clips or clasps are used at the first maxillary molars to snap on to the teeth. A labial arch wire fits over and extends between the maxillary canines in an attempt to avoid splaying of the teeth, and a cingulum arch wire is provided to try and prevent eruption of the maxillary canines.
In U.S. Pat. No. 5,117,816 another type of device is shown. This thermoplastic implement substantially covers the entire maxillary dentition and has a lower surface portion which includes a downwardly extending flange intended to extend into the lingual vestibule of a user in order to maintain a forward posture of the lower jaw. An airway passage is centrally located to allegedly permit adequate breathing through the mouthpiece if nasal blockage is present.
The main problem with both of these devices is the pressure applied to the teeth of the user. Both appliances use the teeth to a significant degree to obtain the open and extended position of the mandible. The device of the '737 patent receivingly engages the mandibular incisors to cause the mandible to protrude forward, whereas the downwardly extending flange of the '816 patent apparatus serves to maintain the forward position of the mandible by similarly contacting the rear of a user's lower front teeth. Besides the general discomfort caused by the stressing of the teeth, permanent repositioning of the teeth may occur if undue pressure is applied for too long a duration. Another problem common to both appliances is that they can only be used in connection with the presence of dentition, either natural or prosthetic.
Other problems with the device of the '737 patent include the time and cost associated with its fitting and manufacture. The fitting and manufacture of the device can only be accomplished by a professional, and quickly becomes comparatively expensive. Time is spent by the professional in determining through trial and error the appropriate fit for the user. Then, molds are taken of the maxillary and mandibular dentition, and such molds are mounted in the recorded position for the formation of a template. The appliance is then cast of a heat curable plastic (acrylic) with the crosswires and arch wires embedded in the casting material.
The device also covers the entire mandibular dentition and includes a continuous semicircular lingual flange which extends downwardly into the lingual vestibule giving an unusual and cramped feel to the tongue. Further, the presence of crosswires and arch wires invites manipulation by the tongue which may lead to tongue sensitivity or other soreness. Further, as it is made of a hard plastic, the device is unyielding as far as allowing slight movement for swallowing or allowing the stretching or working of the jaw muscles.
The apparatus of the '816 patent, while made of a thermoplastic material, consists of an upper surface portion only that substantially covers the entire maxillary dentition with a lower surface portion extending downwardly into the lingual vestibule. Stabilization of the mandible in the forward position is supposedly effected by the position of the downward flange. The degree of stabilization which can be maintained, however, necessarily varies to the degree the mandible is opened or closed by the user. As the user's mouth opens and closes to any extent, the flange will ride up and down the lingual side of the lower front teeth. Further, while the device does contain an airway passage, the passage is surrounded by a concave portion on the rear face of the flange to provide a space for forward positioning of the tongue. But this forward positioning of the tongue will block the air passage forcing the user to breath through the nares.